Effect Of Dissolution Of Magnesite And Dolomite On Its Floatability

The useful mineral in magnesite ore is magnesite,and gangue mineral is mainly silicon containing mineral mainly composed of quartz,talc and chlorite,calcium containing mineral mainly composed of dolomite,and iron containing mineral mainly composed of magnetite and hematite（limonite）.Silica containing gangue such as quartz and silicate minerals in magnesite are generally removed by reverse flotation,but magnesite and dolomite belong to carbonate minerals,both of which are natural hydrophilic salt minerals,with very similar crystal structure and chemical properties.The only difference is that there are different cations in their lattice,The solubility of magnesite and dolomite is different under different dissolution conditions,and the surface properties change after dissolution.Therefore,it is of great significance to explore the dissolution and floatability of magnesite and dolomite under different dissolution conditions for the separation and regulation of magnesite and dolomite.During the test,the dissolution of magnesite and dolomite under different reagent dosage,dissolution time and other conditions was investigated in H₂O,HCl,H₂SO₄,HNO₃,C₆H₈O₇,C₂H₄O₂,Na OH and other dissolution environments,and further the changes in the floatability of magnesite and dolomite dissolved in various dissolution systems under different p H,the dosage,adjustment,type and dosage of collector LKD,and the presence of Ca²⁺and Mg²⁺.The test results show that when the dosage of reagent is 26.37 g/L and the dissolution time is 15 min,the solubility of magnesite is maximum after adding H₂SO₄,the solubility of dolomite is maximum when adding HCl,and the solubility of both is minimum when adding Na OH.Under the corresponding optimum p H conditions,when the dosage of collector is 15 mg/L,the recovery rates of magnesite and dolomite after dissolving in different dissolving environments are both 50%～75%.In the C₂H₄O₂ dissolution system,when the amount of sodium hexametaphosphate is 15 mg/L,the recovery rates of magnesite and dolomite are significantly different,which are 72.79%and 50.16%respectively.At the same time,the presence of Ca²⁺will inhibit the flotation of magnesite after dissolution under various dissolution conditions.The surface of magnesite and dolomite before and after dissolution was characterized in situ by means of in-situ contact angle,electrokinetic potential,infrared spectroscopy,scanning electron microscopy and other detection methods,so as to judge the reagent adsorption of magnesite and dolomite after dissolution in different dissolution environments.The results showed that the surface contact angles of magnesite and dolomite changed greatly in the C₂H₄O₂ dissolution system,and the contact angles after dissolution were 35.96°and 34.91°.The zero electric point of magnesite and dolomite will shift before and after dissolution.When collector LKD acts with the dissolved magnesite and dolomite,the zero electric point of both will shift to the right,moving in a positive direction as a whole with different movements.The corresponding characteristic peak areas in the infrared spectrum before and after the dissolution of magnesite and dolomite changed,and there were N—H characteristic peaks after interaction with LKD.The results of scanning electron microscopy showed that the surface element contents of the two samples changed before and after dissolution,and N existed on the surface after interaction with LKD.Therefore,magnesite and dolomite exhibit different dissolution behaviors in different dissolution environments,and the-NH²⁺or-OH group in LKD will have physical adsorption or hydrogen bond with O or H atoms on the surface of magnesite and dolomite binding effect.